Collapsible air filtering device

1. An air filtering device comprising:

a base having an air inlet and an air outlet;

a fan functionally attached to said base,

an air filter in air flow communication with said air outlet;

an air impermeable outer sleeve wherein said outer sleeve comprises a first open end, a second open end, and an air flow path therebetween, wherein said outer sleeve is in air flow communication with said air outlet and is releasably attached to said base at said first open end, and wherein said outer sleeve envelops said air filter around its longitudinal axis when attached to said base, and wherein said outer sleeve is configured to be collapsible when said outer sleeve is not attached to said base.

2. The device of claim 1 wherein said outer sleeve collapses to about 30% of its upright configuration.

3. The device of claim 1 wherein said outer sleeve expands to an upright configuration and is frame-less.

4. The device of claim 1 wherein the exit velocity of air exiting said second open end of said outer sleeve is about 0.8 m/s to about 2.6 m/s.

5. The device of claim 1 wherein the exit velocity of air exiting said second open end of said outer sleeve is about 0.8 m/s to about 1.8 m/s.

6. The device of claim 1 , wherein the air flow rate exiting said second open end of said outer sleeve is at least about 60% of the air flow rate entering said first end of said outer sleeve.

7. The device of claim 1 , wherein said air filter bag does not contact said outer-sleeve while said device is activated.

8. The device of claim 1 , wherein said fan provides an air flow rate of about 70 to about 150 CFM at about 4 to about 25 Pa of pressure.

9. The device of claim 1 , wherein said fan provides an air flow rate of about 80 to about 120 CFM at about 10 to about 25 Pa of pressure.

10. The device claim 1 , further comprising a power source providing less than about 25 Watts of power to activate said fan.

11. The device of claim 1 , wherein the air filter has tapered sidewalls.